Question

A current is flowing in a long wire. It is first shaped as a circular coil of
one turn, and then into a coil of two turns of smaller radius. Will the magnetic
field at the centre coil change? If so, how much ?

Answer 1

Dear Student,

◆ Answer -

B2 = 4 B1

● Explanation -

Magnetic field at the centre of a coil is given by -

B = μnI/2r

When wire is turned to coil of two turns, n = 1 and r = r₀,

B1 = μ×1×I / 2(r₀)

B1 = μI/2r₀ ...(1)

When wire is turned to coil of two turns, n = 2 and r = r₀/2,

B2 = μ×2×I / 2(r₀/2)

B2 = 2μI/r₀ ...(2)

From (1) and (2),

B2 = 4B1

Therefore, magnetic field at centre of the coil will be four times of the previous.

Thanks dear...